In the early 1970s, birthrates in China were 4.77 per cent. By 2011 the figure had fallen to 1.64 per cent, forcing the government to deal with a combination of a rapidly aging population, a shallow labor pool and an imbalance between the sexes.

China now has the world’s biggest yet most rapidly aging population. By 2050, China will have nearly 440 million over-60s, according to UN estimates.

China's labor pool of 16 to 59-year-olds has been dropping since 2012, and this has coincided with a downturn in economic growth and a rise in unemployment.

Estimates by Chinese officials and some scholars had suggested the relaxation in policy may lead to an increase of up to 2 million births per year, possibly a 10 percent increase – increasing China’s fertility rate from the current 1.6 births per woman to about 1.8 births per woman.

However, it appears the effect is 30-50% of that level.

If China decided to further relax to a “two-child policy,” the number of additional births might reach 5 million annually, with the fertility rate perhaps rising to replacement level. However, the 30-50% level would mean about 2 to 2.5 million added.

With such a rise in fertility, the medium variant, China’s population would peak at 1.45 billion in 2030 and then decline to around 1 billion by the century’s close.

Fully lifting the child restriction policies now might get the additional 5 million births to reach replacement level.

If population policies in China boost child births from 15 million to 23 million for the next 20 years then the China would have 160 million more working age people in 2050. This would prevent a drop of 110 million and perhaps increase the working age population by 5%. Working age population now is about 970 million.

Other ways to deal with the shrinking working age populations would be to increase retirement ages from 64 to say 74. This would keep the working age population stable in the face of 15% drop in overall population in the 15-64 range.

China also has a lower number of people in the urban areas in more productive jobs today. China is also boosting its more productive college educated workforce.

The overall economic impact would be effected by
* how many working age population
* when do people retired
* how urbanized - China will go from 50% to 70-80% in 2050
* how educated and productive is the workforce
* how much automation and efficiency is there